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Code No. C1011 FL wheel speed sensor signal
Code No. C101C FR wheel speed sensor signal
Code No. C1027 RL wheel speed sensor signal
Code No. C1032 RR wheel speed sensor signal
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, Troubleshooting ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
  • When the hydraulic unit assembly (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor and the G and yaw rate sensor (Refer to and ).
 
 
OPERATION
  • The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
  • The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
ASC-ECU monitors the signals from each wheel speed sensor while the vehicle is being driven. If any fault below is found in these sensor signals, ASC-ECU will set the relevant diagnostic trouble code.
  • Irregular change in the wheel speed sensor signal
 
 
PROBABLE CAUSES
Current trouble
  • External noise interference
  • Damaged wiring harness and connectors
  • Malfunction of wheel speed sensor
  • Adhesion of foreign materials on the wheel speed sensor
  • Adhesion of foreign materials on the rotor (for wheel speed detection)
  • Improper installation of the wheel speed sensor
  • Malfunction of the hydraulic unit assembly (integrated with ASC-ECU)
  • Deformation of the wheel speed detection magnetic encoder
  • The number of poles on the wheel speed detection magnetic encoder is changed
  • Disturbance of magnetization pattern for wheel speed detection encoder
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between ASC-ECU and the wheel speed sensor. For diagnosis procedures, refer to How to treat past trouble (GROUP 00, How to Cope with Intermittent Malfunctions ).
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus lines.
Use scan tool (M.U.T.-III) to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus line (Refer to GROUP 54C, Troubleshooting ). On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after repairing CAN bus lines
Is diagnostic trouble code No. C1011, C101C, C1027 or C1032 set?
Go to Step 3.
The procedure is complete.
 
STEP 3. Using scan tool (M.U.T.-III), check data list.
Check the following data list (Refer to ).
  • (When code No. C1011 is set) Item No.01: FL wheel speed sensor
  • (When code No. C101C is set) Item No.02: FR wheel speed sensor
  • (When code No. C1027 is set) Item No.03: RL wheel speed sensor
  • (When code No. C1032 is set) Item No.04: RR wheel speed sensor
Is the check result normal?
Go to Step 7.
Go to Step 4.
 
STEP 4. Harness and connector check
(1) Check the wheel speed sensor (FL, FR, RL or RR).
(2) Check the ASC-ECU connector.
(3) Check the wiring harness and connector between the ASC-ECU connector and the wheel speed sensor (FL, FR, RL or RR).
Is the check result normal?
Go to Step 5.
Repair the defective connector or the wiring harness. Then go to Step 8.
 
STEP 5. Check of wheel speed detection magnetic encoder are installed properly
Check whether the wheel speed detection magnetic encoder relevant to code No. is installed correctly (adhesion of foreign materials, deformation, etc.).
 
Diagnostic trouble code No. Relevant sensor
C1011Front left
C101CFront right
C1027Rear left
C1032Rear right
Is the check result normal?
Go to Step 6.
<when the relevant wheel is front> : Remove the foreign materials and clean the encoder so as not to disturb the magnetization pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. If deformation is found, replace the wheel bearing (Refer to GROUP 26, Front Axle Hub Assembly ). Then go to Step 8.
<when the relevant wheel is rear> : Remove the foreign materials and clean the encoder so as not to disturb the magnetization pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. If deformation is found, replace the pulse rotor (Refer to GROUP 27, Rear Axle Hub Assembly ). Then go to Step 8.
 
STEP 6. Check for wheel speed sensor as a single unit
Check the wheel speed sensor (Refer to ).
Is the check result normal?
Go to Step 7.
Replace the wheel speed sensor (Refer to ). Then go to Step 8.
 
STEP 7. Check whether the diagnostic trouble code is set again.
Check again if the diagnostic trouble code is set.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: "LOCK" (OFF) position to "ON"
(3) Drive the vehicle until the vehicles speed reaches 20 km/h (12 mph).
Is diagnostic trouble code No. C1011, C101C, C1027 or C1032 set?
Replace the hydraulic unit assembly (integrated with ASC-ECU) (Refer to ). Then go to Step 8.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 8. Check whether the diagnostic trouble code is set again.
Check again if the diagnostic trouble code is set.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: "LOCK" (OFF) position to "ON"
(3) Drive the vehicle until the vehicles speed reaches 20 km/h (12 mph).
Is diagnostic trouble code No. C1011, C101C, C1027 or C1032 set?
Return to Step 3.
This diagnosis is complete.